Double-walled heat exchanger tubes are basically known for motor vehicle air conditioning systems. For example, DE 10 2005 052 972 A1 discloses a double-walled heat exchanger tube running between the capacitor and expansion valve of a motor vehicle air conditioning system. The double-walled tube here forms part of a high-pressure tube for transporting a high-pressure coolant issued by the compressor, as well as part of a low-pressure tube for transporting a low-pressure coolant from the evaporator to the compressor. The double-walled heat exchanger tube here has an outer tube and inner tube. The inner tube runs in the outer tube in such a way as to penetrate through the outer tube. The longitudinal end sections of the outer tube have a reduced diameter, so as to form reduced connecting parts. These reduced connecting parts of the outer tube are directed radially inward, and welded with the inner tube in a liquid or air tight state. In this way, the outer tube and inner tube define a fluid-carrying channel.
Soldering or welding the inner and outer tube is a relatively complex procedure from a production standpoint. It uses a separate welding or soldering procedure provided for this purpose. The soldered or welded junction also constitutes a weak point in the high-pressure coolant circulation. In order to ensure adequate tightness, the welded or soldered junction just be fabricated with the greatest possible precision. Further, such soldered or welded junctions are susceptible to corrosion precisely during long-term operation.
Therefore, at least one object is to provide an improved joining of the ends of a coaxial heat exchanger tube that from the standpoint of assembly is especially easy and inexpensive to realize, and also exhibits an improved corrosion resistance. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.